R语言实现统计plink格式数据基因频率

1、

dir()
dat <- read.table("outcome.ped")
dat <- dat[,-(1:6)]
loci <- data.frame()
loci[1:(nrow(dat) * 2), 1] <- 1

for (i in 1:(ncol(dat)/2))
{
    loci <- cbind(loci, c(dat[, 2*i -1], dat[,2 * i]))
}
loci <- loci[, -1]

colnames(loci) <- paste0("c",1:8)
result <- data.frame()
temp <- vector()
for (i in 1:ncol(loci)) 
{
  locidat <- as.data.frame(table(loci[,i]))
  if (nrow(locidat) == 1 & locidat[1, 1] == 0 ) {
    temp <- c(0, 0, 0, 1)
  }else
  if (nrow(locidat) == 1 & locidat[1, 1] != 0 ){
    temp <- c(0, 0, as.character(locidat[1, 1]), 1)
  }else
  if(nrow(locidat) == 2) {
    locidat <- locidat[order(locidat$Var1),]
    if (locidat[1, 1] == 0) {
      temp <- c(0,0, as.character(locidat[2,1]), 1)
    }else
    {
      locidat <- locidat[order(locidat$Freq),]
      temp <- c(as.character(locidat[1,1]), locidat[1,2]/sum(locidat$Freq), as.character(locidat[2,1]), locidat[2,2]/sum(locidat$Freq))
    }
  }else
  if (nrow(locidat) == 3){
    locidat <- locidat[locidat$Var1 != 0, ]
    locidat <- locidat[order(locidat$Freq),]
    temp <- c(as.character(locidat[1,1]),locidat[1,2]/sum(locidat$Freq), as.character(locidat[2,1]), locidat[2,2]/sum(locidat$Freq) )
  }
   result <- rbind(result, temp) 
}

for (i in c(2,4)) {
  result[,i] = round(as.numeric(result[,i]),5)
}


map <- read.table("outcome.map")
result <- cbind(map[,c(1:2,4)], result)
colnames(result) <- c("chr", "snp", "pos", "minor", "freq", "major", "freq")
result
write.csv(result, "result.csv", row.names = F)
dir()

2、plink软件验证

[root@centos79 test]# plink --file outcome --freq --sheep --out verify >/dev/null; rm *.log *.nosex
[root@centos79 test]# ls
outcome.map  outcome.ped  verify.frq
[root@centos79 test]# cat verify.frq
 CHR  SNP   A1   A2          MAF  NCHROBS
   1 snp1    0    G            0       12
   1 snp2    G    C          0.2       10
   1 snp3    0    0           NA        0
   1 snp4    0    G            0        8
   1 snp5    A    G       0.3333       12
   1 snp6    A    T          0.5       12
   1 snp7    A    G       0.4167       12
   1 snp8    G    C       0.4167       12